The present invention is directed toward a tripod and more particularly toward a tripod of the type utilized over a manhole or the like to aid in the introduction or removal of a workman or equipment into or out of the hole and which includes an alarm therein which emits a signal whenever a weight suspended from the tripod exceeds a predetermined level. The tripod of the invention can, therefore, be utilized to indicate when a workman has fallen and needs assistance.
The invention has particular use with fall protection devices such as shown in Applicant's U.S. Pat. No. 4,511,123. Such devices are personal fall arrest systems which are used in conjunction with other components such as a tripod or the like for anchoring the device and a body harness which is worn by a workman.
Safety devices of this kind are normally comprised of a housing which is adapted to be suspended from either an elevated structure or from a tripod or the like above a manhole. A rope or cable winding drum is rotably mounted in the housing and a spiral spring drives the drum in a direction which continuously tends to wind the cable around the drum. A centrifugally operated brake mechanism reponds to an initial fast rotation of the drum in the unwinding direction and brakes the rotation of the drum to prevent further unwinding thereof.
In use, these safety devices are fixed to a structure such as a building, bridge or the like and the cable extending therefrom is fastened to a worker's belt or harness. Under normal working conditions, i.e. as the worker moves from one place to another and the rope is drawn in and out of the housing at a reasonable speed, the centrifugal brake is never engaged since the speed of rotation of the drum is relatively slow. Accordingly, the drum rotates freely and the rope is drawn out or wound on the drum freely. In the event of a fall, however, the rope is drawn out rapidly and the drum is then rotated at a high speed. As a result, the centrifugally operated brake is actuated preventing further rotation of the drum which stops the rope from being drawn out. This prevents injury or death to the worker which otherwise would occur as a result of the fall.
When a worker has fallen and is being suspended by the rope from the safety device, he may be able to climb to safety or he may have to be lifted using either auxiliary lifting equipment or by utilizing the lifting portion of Applicant's safety device shown in U.S. Pat. No. 4,511,123. There are times, however, when a workman may fall and need assistance to be lifted to safety but when his co-workers may not be aware of his need for assistance. This may occur, for example, when such a safety device is utilized with a tripod for allowing a workman to descent into a manhole or similar confined space. Since the workman is not in view, his co-workers would not be aware that he has fallen and needs assistance, particularly if he is injured to the point that he cannot call out for help. In view of the fact that the environment in which such workers are normally operating may contain hazardous substances, it is often important to lift the fallen worker as quickly as possible.
To the best of Applicant's knowledge, no one has ever attempted to devise a system for addressing the problem which Applicant's invention solves. Heretofore, it has always been necessary for a second worker to remain on the ground directly next to the tripod to constantly observe the safety device to determine whether the braking mechanism has been activated by a worker falling. This not only requires additional man power but is often ineffective at night since it is difficult to observe the cable and safety device.